A circuit may be used to act as an output driver to provide output signals from a device to a load. The output driver may be configured to provide a desired output signal (e.g., for digital devices, the output driver may be used to provide desired xe2x80x9chighxe2x80x9d and xe2x80x9clowxe2x80x9d output signal levels). Often it is desirable to have the impedance of the output driver to match the impedance of the driven load.
The accuracy of existing output drivers can be affected by temperature variations. For example, an output driver may be formed from a switch (such as a transistor) and one or more resistors. The effective resistance of each of these devices can vary with fluctuations in temperature. For example, the effective drive state resistance of an output driver typically increases with increases in temperature. As the temperature varies, and the effective impedance of the output driver increases, the output signal integrity is reduced. An output driver which is designed to produce a desired output signal may have, for example, an effective resistance of 50 ohms. This effective resistance can rise 1-10 ohms as the operating temperature increases, resulting in an undesirable variation in the output impedance produced by the driver. The resulting impedance mismatches between the output driver and the driven load results in undesirable signal variations.